The present invention relates to a new and improved construction of tool or tool changing device for horizontal drilling-milling machines of the type incorporating a magazine located adjacent the machine in which there are arranged the tools horizontally and at right-angles to a tool spindle, there also being provided a gripper rocker or balance equipped with a gripper rocker shaft mounted parallel to the tool spindle in a gripper carriage which is displaceable in the direction of the tool spindle for the introduction and removal of the tools and which possesses a doubly pivotable gripper vane or wing which is rotatable through an angle of 180.degree..
With heretofore known tool changers of such type (known in the trade under the designations HELLER BEA, BURR TC 22, BOHLE W 1) each gripper tong or clamp is displaceable through the agency of a gripper slide arranged in the gripper vane rotatable at the gripper rocker. With both of the first mentioned tool changers during the first operating phase there is carried out a tool change of the "new" tool out of the magazine by means of a gripper slide and such is then transferred into a so-called park position where it stands ready at the tool spindle for the tool change after the presently continuing working operation with the "old" tool has been terminated. For transferring the "new" tool out of the park or distribution position into the tool spindle, with the three previously mentioned constructions of tool changing devices the gripper vane initially is rocked by the gripper rocker in front of the headstock and thereafter the empty gripper tong is displaced out of the gripper vane by means of its gripper slide in order that it can engage the old tool located in the tool spindle. After the axial ejection out of the tool spindle by means of the gripper slide for the purpose of returning the old tool the corresponding gripper slide initially is retracted into the gripper vane, whereupon the gripper rocker or balance is pivoted back out of the region of the headstock. For the transfer from the park or distribution position into the tool spindle position and vice versa there are also required two respective functional steps with two respective acceleration- and two respective deceleration phases which are carried out in succession since the momentary thrust movement of the gripper slide during the infeed first can occur after the pivotal operation of the gripper rocker has terminated and during the return movement the pivoting back of the gripper slide first can occur after the gripper arms have been retracted.
This type of infeed and retraction of the tools with a pivotal guide, two gripper slides located in a rotatable gripper vane, with two associated longitudinal guides as well as a longitudinal guide for the introduction and removal of the tools is time-consuming, complicated and prone to disturbances, especially if there is considered that longitudinal guides generally are more complicated and sensitive to casting dust as well as chip fly or dust than pivotal guides.
These prior art constructions in the case of small workpieces which are clamped centrally at the workpiece table do not permit the tool exchange operation in the lower region of the Y-position of the tool spindle above the workpiece table, because the axis of rotation of the gripper vane during the tool exchange is located in a horizontal plane with the tool spindle. Consequently, in such instances the workpiece table and the machine frame, respectively, must be displaced further than is necessary for achieving an accessible position, likewise resulting in losses in time. This drawback is particularly then present when the catch plate of the chip transport installation is extended upwardly between the workpiece table and the machine frame in an advantageous manner to the table support surface.
The discussed tool changers are components of the machine, in other words installed at the machine frame or stand. Thus it is not readily possible to selectively fabricate in a rational manner the machines with or without the tool changer. Additionally, there are possible deleterious effects upon the accuracy of the machines, since for instance during the working operation which is in progress there must occur at the magazine functional steps or operations for the next tool change.
A different but related type of tool changer for horizontal drilling-milling machines equipped with a headstock displaceable in the spindle direction is erected adjacent the machine and independently thereof (known as SAALFELD C 101 NC). For the tool change operation the headstock is always displaced into its rearward terminal position in which the tool spindle is positionally related to the tool changer. The drawbacks mentioned in the immediately preceding paragraph are in this case avoided, but however there exists the drawback that in the case of short and average length tools as well as in the case of smaller workpieces clamped at the center of the table the spindle slide or carriage must move through an unnecessarily long distance for the tool change operation. Consequently, there are present losses in time and increased wear and tear with respect to the spindle carriage guide responsible for the working accuracy of the machine. Additionally, what is disadvantageous is that the tool gripper requires a special stand or frame in order to be able to carry out the tool change operation in each elevational position of the spindle carriage.
A further related type of tool changer for horizontal drilling-milling machines equipped with a machine frame displaceable in the spindle direction is likewise erected independent of the machine (known as KEARNEY & TRECKER MODU-LINE). For the tool change operation in this case the machine frame is displaced into its rearward terminal position where the work spindle is positionally related with respect to the tool changer. The indicated disadvantages present when the tool changer is mounted at the machine are equally avoided, but instead there also exists in this instance the drawback that when handling short and average length tools and smaller workpieces the machine frame must carry out an unnecessarily long displacement for the tool change operation.
In the case of a tool changer of a different type for vertical drilling-milling machines, which likewise is erected independently adjacent the machine, the tools are horizontally maintained in a disk magazine. In this regard attention is directed to German Pat. No. 2,110,943. During the first phase of a tool change operation a magazine spindle sleeve or tail spindle displaces at the magazine the new tool at a change head (gripper vane) rotatable through 180.degree. which contains the tool gripper and mounted at the end of a carrier which --similar to the case of industrial robots-- is pivotable and rotatable through 90.degree. as well telescopically displaceable. During the further course of the operation the new tool is brought into the park or distribution position by simultaneously pivoting and rotating the carrier. The transfer of the new tool out of the park position to the tool spindle --as well as vice versa-- occurs by means of the telescopic displacement of the carrier. For the axial ejection as well as introduction of the work at the work spindle both of the gripper tongs or clamps at the change head are additionally displaceable by means of a respective gripper slide and associated guides. This tool changer is only suitable for machines with vertical work spindle and it avoids the drawbacks of the previously mentioned constructions. With respect to the considered portion of the course of the movement it however requires one tail spindle displacement, one carrier displacement, two gripper displacements, one carrier rotation, and one carrier pivoting movement. Since the carrier is pivotable at a special support frame, located between the machine and the magazine, there are present drawbacks with this solution in terms of its very great constructional expenditure and very great spatial requirement. Additionally, there is rendered more difficult positive guiding and actuation of the gripper tongs or clamps in the change head owing to the locally tight spatial conditions. It is for this reason and because of the telescopic-type displacement of the carrier with large projection or cantilever lengths that it is not possible to use large and heavy tools.